Fuel systems are used to deliver fuel to one or more storage tanks and to enable sealed storage of the fuel in the storage tanks. Shutoff valves are often used to control flow between the storage tanks and/or between portions of the tanks, which may be interconnected. Ball valves controlled by electromagnetic motors are typically used, such as due to low cost, efficiency, and availability. Such electromagnetic motors provide high speed to quickly enable or cut off flow through associated shutoff valves.
For use in aerospace applications, such as in connection with fuel tanks of an aircraft, spacecraft, or a combination thereof, such electromagnetic valves, providing high speed and also low torque, are often coupled to several stages of gears. This coupling slows down the rotational speed and amplifies the output torque of the electromagnetic actuators of the electromagnetic valves. In this way low speed and high torque are obtained, which are needed to overcome frictional and fluid induced forces moving through and valves and to prevent an excessively high surge pressure induced by a sudden stop of the fluid flow through the valves.
As a consequence, inertia, hysteresis and backlash associated with the use of the stages of gears often slows down the response time, decreases the positioning accuracy, and introduces extra noise and impact loads with respect to the associated ball valves. The use of the gears also increases the part count, cost and weight in the associated bill of materials and introduces components requiring replacement and/or maintenance.
In addition, electromagnetic motors typically rely on magnetic fields generated, such as by permanent magnets or by current flowing through windings, to convert electromagnetic energy into mechanical energy. In the case of aerospace applications where electromagnetic interference must be minimized, additional components are necessary to address the EMI concerns, further increasing cost and complexity of associated fuel delivery systems.